Hydraulic back-pressure arrester



June 6, 1939. M. P. DE MOTTE 2,161,700

HYDRAULIC BACK-PRESSURE ARRESTER Filed Feb. 29, 1936 Z SheetS-Sheet 1 I INVENTOR I MAO/W05 A .0! H0772! l BY ATTORNEY June 6, 1939. M. P. DE MOTTE HYDRAULIC BACK-PRESSURE ARRESTER Filed Feb. 29, 1956 2 Sheets-Sheet 2 ATTORNEY Patented June 6, 1939 UNITED STATES PATENT OFFICE Maurice P. De Motte, Indianapolis, Ind., assignor to Oxweld Acetylene Company, a corporation of West Virginia Application February 29, 1936, Serial No. 66,415

11 Claims.

This invention relates to hydraulic back-pressure arresters which are employed in combustible gas supply lines to prevent the return flow of gas through the line to the source of supply of the combustible gas. More specifically this invention relates to hydraulic back-pressure arresters employed in fuel gas systems which supply an oxygen fuel gas combustion apparatus, and more particularly to hydraulic back-pressure arresters employed in conjunction with acetylene generators. Such hydraulic back-pressure arresters, which are also termed flash-back arresters, are used to prevent a return flow of oxygen from the combustion apparatus to the acetylene generator and also to prevent a flash-back occurring in the combustion apparatus from traveling through the supply line back to the generator.

Hydraulic back-pressure arresters, as employed in acetylene generating systems, have heretofore usually included a liquid or water-sealed checkvalve at the inlet of a flash-back chamber interposed in the supply line between the acetylene generator and the combustion apparatus. In addition, a suitable pressure relief valve has usually been connected to the flash-back chamber to discharge into the atmosphere any undue amount of high pressure oxygen flowing back into the chamber, or to relieve any excessive gas pressure resulting from the explosion of an oxyacetylene gas mixture which might have accumulated in the outlet piping of the system.

The operation of such apparatus is not entire- 1y dependable, since the supply of sealing water may become depleted or entirely lost due to the tendency of commercial check-valves to leak or to other causes. One instance of such depletion may occur when the pressure at the outlet becomes greater than the pressure at the inlet of the hydraulic arrester when the generator is opened for recharging and the pressure within the generator is thereby reduced to atmospheric pressure, or when an obstruction at the blowpipe nozzle or in the combustion line causes a diversion of high-pressure oxygen into the fuel gas delivery line, and the check-Valve leaks and ermits the water to be forced out of the arrester; another may occur when a sudden reversal of pressure, due to a flash-back in the delivery system, forces a portion of the water in the arrester back through the check-valve before the check-valve has an opportunity to close and prevent such loss of Water; another may occur when the volume and velocity of the acetylene delivered through the arrester is sufiiciently great to cause a violent agitation of the Water and also to cause a considerable amount of water to be splashed into the outlet of the arrester, from whence it will subsequently either flow or be carried by the acetylene into the delivery line; and still another may occur when the supply of sealing water is reduced by moisture being entrained by the gas bubbling through the water. In the event that the sealing water becomes entirely lost, usually due to a combination of the aforementioned causes, the arrester then will 10 afford scant protection, since flash-backs or explosions tend to pass through check-valves devoid of sealing water, and thus the flash-backs or explosions will be substantially free to travel through the arrester into the generator. 15

The objects of this invention, therefore, are to provide an improved hydraulic back-pressure arrester adapted for use with supply lines for combustion apparatus or with acetylene generators, which will effectually prevent the loss of sealing liquid due to a leakage of gas or liquid back through the check-valve; to insure at all times a reliable seal between the inlet and outlet of the arrester; to reduce the loss of liquid due to entrainment of moisture by the combusti- 25 ble gas when flowing through the apparatus; and to prevent the loss of liquid due to splashing which occurs when the liquid becomes violently agitated due to the passage through the liquid of large volumes of combustible gas or acetylene at a high velocity. These and other objects and the novel features of this invention will become apparent from the following description and accompanying drawings in which:

Fig. 1 is a vertical sectional view of apparatus embodying this invention and adapted to be installed in the gas chamber of an acetylene generator;

Fig. 2 is a horizontal sectional View taken along line Z2 of Fig. 1 and illustrating more clearly the spacer shown in the upper portion of the' apparatus of Fig. 1;

Fig.3 is a horizontal sectional view, taken along line 3-3 of Fig. 1;

- Fig. 4 is a vertical sectional View corresponding to Fig. 1 but reduced in size and illustrating the position of the liquid in the apparatus when the pressure at the outlet is greater than the pressure at the inlet;

Fig. 5 is a verical sectional view of a modifica' tion of the apparatus shown in Fig. 1, installed within the shell of an acetylene generator; and Fig. 6 is a front view of a filter and holder of the apparatus shown in Fig.5.

The improved hydraulic back-pressure arrester shown in Fig. 1 comprises a tubular metal casing C having an inlet conduit I connected to and extending into the casing through an inlet at the lower end, and an outlet conduit connected to the casing adjacent the upper end. The casing is adapted to be installed partially within the gas chamber of an acetylene generator, whose shell G is shown by broken lines. At the lower end of the inlet conduit I is a check-valve V which is disposed within the gas chamber of the acetylene generator. The inlet conduitv I includes a pipe 6 which extends through the lower end of the casing C and into the upper portion thereof. The pipe 6 is preferably centrally located within the casing and may be attached to the casing in any liquid-tight manner, such as by welding. Positioned about the pipe 6 and within the casing is an inverted bell or capped tube 8 having its closed upper end 9 disposed above the upper end of pipe 6. A rod 1 secured to the upper open end of pipe 6 may serve to position bell 8 about pipe 6 and also assist in holding pipe 6 in position. The bell 8 may be provided with a plurality of holes ill adjacent its'lower end and also may be totally enclosed by means of a washer I I which is adapted to fit about pipe 6 and may be fastened to the pipe and the bell in any convenient manner, such as by welding, to hold the bell stationary. An annular space A is formed between the bell and the inlet pipe and an annular space E between the lower portion of the bell and the casing C. The lower end of bell 8 is normally immersed in a body of sealing liquid I 2, usually water, which is disposed within the spaces A and B and has a filling level [3. The water may be introduced into the casing by means'of a filling connect-ion F attached to the casing at the filling level and extending through the shell of the gas compartment of the generator. A screw plug S is adapted to be inserted into the end of connection F outside the generator shell so as to close the connection when the hydraulic arrester is in operation. A drainage connection D, adapted to be closed by a plug P and secured to the casing at its lower end, extends through the shell of the gas chamber of the generator.

Disposed between the upper portion of the bell and the casing C is a series of bafiles I4, I5, l6 and I1. Each of these baffles is alternately inclined at a small angle to'the bell, and may be attached thereto by means of welding. As is more clearly illustrated in Fig. 3, each of the baflies extends for a greater portion of the distance around the bell, thus leaving openings I4, l5, l6 and H between the bell and the casing. These openings are located at the lower end of each bafiie and since the baflles are alternately inclined, the openings will also occur alternately. The lowest baffle I4 is disposed a sufficient distance above the filling level of the body of water so as to be above water level when the water in space A is forced down to the level of holes if and into space B. The baflles serve not only to provide a circuitous path for the gas passingbetween them but also are adapted to hold the bell 8 in its preferably concentric relation to the casing.

In the upper portion of casing C and disposed above the upper end9 of bell 8, are two parallel rods 8 which support a screen l9, which in turn supports felt discs 20 adapted to remove particles of foreign matter and entrained moisture from any gas passing therethrough. The felt discs are held in position by a spacer 2|, shown more clearly in Fig. 2, which is adapted to prevent the felt, which has a tendency to swell upon absorbing moisture, from clogging the outlet of the casing. A cap 23, secured to the casing by bolts 24 and sealed by a gasket 22, provides an easy means of access to the upper portion of the casing for the purpose of replacing the felt, if necessary. Secured to the casing, preferably at a point above bell 8 but below the screen !9, is a relief valve connection R to which may be attached any suitable pressure relief valve (not shown).

In general, the modified embodiment of this invention, as shown in Fig. 5, is similar to the construction disclosed in Figs. l3, inclusive. The principal differences are that the filter is mounted on the back pressure arrester ahead of the check-valve V in the inlet conduit I thereof, so as to exclude carbide dust as well as entrained moisture from the acetylene before the latter enters the arrester, thus preventing the clogging of passages in the arrester due to an accumulation of residue therein; and the generator shell is constructed so as to provide an easy means of access to the filter so that the filter discs may be cleaned or replaced, if necessary.

In the modification shown in Fig. 5 the acetylene generator shell G may be constructed so as to form upper and lower sections providing an upper gas compartment U and a lower compartment L. The upper compartment U is adapted to contain the hydraulic back-pressure arrester and a carbide hopper (not shown) and the lower compartment L is adapted to contain, in the lower portion thereof, a body of water (not shown) into which calcium carbide from the carbide hopper may be fed in order to generate acetylene gas. The acetylene thus generated will contain not only moisture but also calcium carbide dust or small particles of reacted carbide.

To collect the generated gas, the inlet conduit I may extend into the upper portion of the lower compartment, above the normal level of the body of water contained therein; and, to remove the dust, filter discs 20' may be mounted in the inlet conduit ahead of check-valve V by means of a holder 3| of substantially greater diameter than a pipe 32 connecting the holder to the checkvalve. The holder 3| may be provided with an open inlet end, and an outlet end plate 33 having a single opening 34 therein. adapted to permit the holder to be secured to pipe 32 in a gas-tight manner, such as by welding. The holder 3!, by reason of its greater diameter and open inlet end, is particularly adapted to collect and deliver the generated gas to pipe 32. The felt discs 26' may be positioned within the holder, between an inner screen 35 and an outer screen 35. Inner screen 35 may be attached to holder 38 in a position spaced from outlet end plate 33 in any suitable manner, such as by tack welding. To enable the felt discs to be clamped in place or removed for cleaning or changing, holder 3! and screen 36 are provided with an equal number.

of lugs 31 and slots 38, respectively, which are so positioned around the peripheries of the holder and the screen that when slots 33 register with lugs 37, screen 36 may be pressed toward screen 35, and then turned by a handle 35? into the position shown in Fig. 6, in which the screen. is tightly held in position by lugs 31 and the pressure of felt discs 20.

The check-valve V may be connected to inlet pipe 6 by an elbow 40, a nipple 4|, and a union 5?. The inlet pipe 6 leads into casing C, which may be provided with inlets and outlets as the casing of Fig. 1. The interior construction and parts included in the casing C of Fig. 5 are similar to those of Figs. 1-3 with the exception that the rods, screen, discs and spacer situated in the upper portion of the casing of Fig. 1 may be omitted in the modification shown in Fig. 5. A cap 43 may be secured to the casing C in any suitable manner, such as by welding.

To provide access to holder 3i for the purpose of inspecting, cleaning or replacing felt discs 20', or inspecting or replacing check-valve V, the upper and lower sections of the generator shell may be provided with a pivot hinge 44 by means of which the upper section may be swung upwardly and, since the arrester and inlet line are entirely supported by the upper section, holder 31 and check-valve V will thereby be raised out of and above the lower section, as indicated by dotted lines T in Fig. 5, showing the upper section of the casing in open pivoted position.

During normal operation, the upper and lower sections may be secured together by bolts 45 and provided with a gas-tight sealing gasket 46.

The operation of the improved hydraulic. backpressure arrester is as follows: When no acetylene is being generated or used, water may be in troduced through the filling connection F into spaces A and B. The water level in space A will not be as high as that in space B, since gas in space A and inlet I will be compressed during filling because check-valve V will normally prevent the fiow of any gas into the generator. After the water reaches the level I3 in space E the plug screw S may be inserted in the filling connection and the hydraulic arrester thereby sealed off from the atmosphere. Upon the production of acetylene in the generator and the collection of acetylene in the gas chamber a sufficient pressure will be developed so that check-valve V will open to admit acetylene into the inlet I. The acetylene will flow upwardly through the pipe 6 and into the inverted bell 8. As further pressure is built up, water in the space A will be forced into the space B until the level of the water in space A is lowered to the upper portion of holes ID. The acetylene in space A will the-n pass through holes l9 and bubble up through the water in space B to the baffles l4, l5, l6 and I! which will return to the body of water any water splashed up by the passage of large amounts of acetylene, and will also provide a circuitous path which will tend to cause the removal of moisture entrained in the acetylene due to its passage through the body of water. During such normal operation of the arrester, the body of water will assume the position shown in Figs. 1 and 5. After passing around the bafiles, the acetylene will pass into the upper portion of the casing and to the outlet 0 and into the supply line. In the apparatus shown in Fig. 1, the acetylene will also pass through the screen if! and the felt 29 which will remove any entrained moisture which was not removed by the baffies In t1 e apparatus shown in Fig. 5, the felt 223 in the inlet conduit will remove dust and excess moisture contained in the acetylene after its gen eration, and the holder 3| will act as a collector for the inlet conduit I.

In case the pressure at the outlet 0 becomes greater than the pressure at the inlet I (due to the opening of the generator for recharging and the reduction of the pressure within the generator to atmospheric, due to an obstruction in the combustion apparatus and the diversion of high pressure oxygen into the acetylene supply line, or due to the occurrence of a flash-back or explosion in the combustion apparatus) the water normally in space B will be forced into space A, as is shown in Fig. 4. The check-valve V will normally prevent the flow of gas back into the generator, but in case the check-valve leaks slightly or cannot close quickly enough, there will be no loss of water since space A is sufficiently large to contain the entire body of water. Thus there will always be a seal of water between the inlet and outlet, so that flash-backs are prevented from traveling back into the generator, and the relief valve will relieve any undue or excessive pressures occurring in the arrester. When excess pressure at the outlet 0 has been removed and the inlet pressure is once more greater than the outlet pressure, the acetylene will flow through pipe 6 into space A to force the water into space B, and the normal operation of the arrester will then ensue.

While this invention has been described with reference to a particular structure and installation, it will be understood that the hydraulic back-pressure arrester can be applied to apparatus other than an acetylene generator, and also that changes may be made without departing from the scope of this invention.

What is claimed is:

1. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end thereof and an outlet adjacent the upper end thereof, said casing being adapted to hold a body of sealing liquid in the lower portion thereof and also adapted normally to permit the flow of a combustible gas from said inlet to said outlet; a conduit connected to said inlet and extending within said casing to a point above the normal level of the body of liquid, said conduit being adapted normally to direct the flow of gas upwardly from said liquid to the upper portion of said casing; means enclosing said conduit for directing the flow of gas normally downwardly and below the normal level of said body of liquid, said casing and said means forming a space therebetween adapted to contain such body of liquid when said gas flows normally from said inlet to said outlet, and said means and said conduit forming a space therebetween adapted to contain such body of liquid when the pressure of such gas at said outlet is greater than the pressure of such gas at said inlet; and means for in response to changes in the sealing liquid level.

2. A hydraulic back-pressure arrester comprising the combination of a casing having an inlet adjacent the lower end thereof and an outlet adjacent the upper end thereof, said casing being adapted to hold a body of sealing liquid in the lower portion thereof, and also adapted normally to permit the flow of a combustible gas from said inlet to said outlet; a conduit connected to said inlet and extending through said casing to a point within said casing above the normal level of said body of liquid; a check-valve disposed in said conduit adjacent said inlet and normally adapted to permit the flow of such gas into said casing; and an inverted stationary bell within said casing and having the closed upper end thereof disposed above said conduit, said bell also being disposed about said conduit and extending downwardly to a point adjacent the lower end of said casing and below the normal level to a point adjacent the lower end of said casing Preventing movement of said last-named means of such body of liquid, said bell and said conduit forming therebetween a space adapted to contain said liquid when the gas pressure at said outlet becomes greater than the gas pressure at said inlet.

3. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end thereof and an outletadjacent the upper end thereof, said casing being adapted to hold a body of sealing liquid in the lower portion thereof and also adapted normally to permit the flow of a combustible gas from said inlet to said outlet; a conduit connected to said inlet and extending within said casing to a point in the upper portion of said casing above the normal level of such body of liquid; an inverted stationary bell having the closed end thereof disposed above said conduit, said bell enclosing said conduit and extending to a point adjacent the lower end of said casing below the normal level of said body of liquid; and a plurality of baffles disposed between said casing and said bell above the normal level of said body of liquid; and a plurality of baffles disposed between said casing and said bell above the normal level of said body of liquid and holding said bell in its stationary position.

4. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end thereof and-an outlet adjacent the upper end thereof, said casing being adapted to hold a body of sealing liquid in the lower portion thereof and also being adapted to permit the flow of a combustible gas normally from said inlet to said outlet; a conduit connected to said inlet and extending within said casing to a point in the upper portion of said-casing; an inverted stationary bell having the closed end thereof disposed above said conduit and extending downwardly about saidconduit to a point adjacent the lower end of said casing and below the normal level of said body of liquid, said bell having a closed lower end connected to said conduit and a plurality of openings therethrough adjacent the lower end thereof adapted normally to permit the flow of such combustible gas through said body of liquid; a plurality of baflles disposed between said casing and said bell above the normal level of said body of liquid adapted to provide a circuitous path for such combustible gas after passing through such liquid; and means disposed in the upper portion of said casing above said bell adapted to remove moisture entrained in such gas due to passage through said body of liquid.

5. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end thereof and an outlet adjacentthe upper end thereof, said casing being adapted to contain a body of sealing liquid in the lower portion thereof; a conduit connected to said inlet and extending within said casing adapted normally to permit the flow of a combustible gas from said inlet upwardly to the upper portion of said casing; stationary means within said casing enclosing said conduit adapted normally to direct the flow of such gas from said conduit downwardly to a point adjacent the lower end of said casing, and normally to direct the flow of such gas through said body of liquid; means disposed in said casing above the normal level of said body of liquid adapted to remove moisture entrained in such gas due to the passage through said body of liquid; and means for relieving excessive gas pressures within said casing.

63. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end and an outlet adjacent the upper end, said casing being adapted to contain a body of sealing liquid in the lower portion thereof and also being adapted normally to permit the flow of a combustible gas from said inlet to said outlet; a conduit connected to said inlet and extending within said casing to a point above the normal level of said body of liquid; an inverted stationary bell substantially enclosing said conduit and having the closed upper end thereof disposed above said conduit, said bell extending downwardly to a point adjacent the lower end of said casing and having a plurality of holes therethrough adjacent said lower end and below the normal level of said body of liquid; a plurality of i baffles disposed between said bell and said casing above the normal level of said body of liquid and adapted normally to provide a circuitous path for such gas after passing through said liquid; means disposed within said casing in the upper portion thereof above said bell and adapted to remove moisture entrained in such gas due'to passage through said body of liquidyand a checkvalve within said conduit normally adapted to prevent the flow of gas from said casing through said conduit.

'7. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end thereof and an outlet adjacent the upperend thereof, said casing being adapted to contain a body of sealing liquid in the lower portion thereof and also being adapted normally to permit the flow of a combustible gas from said inlet to said outlet; means connected to said inlet and adapted normally to direct the flow of such gas from said inlet to the upper portion of said casing; stationary means enclosing said upwarddirecting means and adapted normally to direct the flow of such gas from said upward directing means downwardly to a point adjacent the lower end of said casing and adapted to direct the flow of such gas through said body of liquid; means disposed within said casing above the normal level of said body of liquid for removing moisture entrained in said gas due to passage through such body of liquid, said means including a screen and a body of felt supported by said screen disposed in the upper portion of said casing above said downward directing means and below said outlet; means disposed adjacent the top of said casing and extending below said outlet adapted to hold said felt against said screen; and a checkvalve adapted to prevent the flow of such gas from said casing through said inlet when the pressure of gas at said outlet becomes greater 3 than the pressure of such gas at said inlet.

8. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end thereof and an outlet adjacent the upper end thereof, said casing being adapted to contain a body of sealing liquid in the lower portion thereof and also being adapted normally to permit the flow of a combustible gas from said inlet to said outlet; a conduit connected to said inlet and extending within said casing to a point in the upper portion thereof above the normal level of said body of liquid; an inverted stationary bell having a closed upper end thereof disposed above said conduit and extending within said casing downwardly about said conduit to a point adjacent the lower end of said casing and below the normal level of said body of liquid, said bell having a plurality of openings therethrough adjacent the lower end thereof adapted normally to direct the flow of such gas through said body of liquid, said bell and said conduit forming a space therebetween adapted to hold said body of liquid when the gas pressure at said outlet becomes greater than the gas pressure at said inlet; a plurality of baifies disposed between said bell and said casing above the normal level of said body of liquid and adapted normally to provide a circuitous path for such gas after passing through said body of liquid; means disposed within said casing above said bell for removing moisture entrained in such gas due to passage through said body of liquid; and a check-valve adjacent said inlet adapted to prevent the reverse flow of gas from said casing through said conduit when the gas pressure at said outlet becomes greater than the gas pressure at said inlet.

9. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end thereof and an outlet adjacent the upper end thereof, said casing being adapted to hold a body of water in the lower portion thereof and also adapted normally to permit the flow of a moisture-laden gas from the inlet to the outlet thereof; an inlet line including a check-valve, a holder for collecting and delivering gas to said checkvalve, and a conduit connected to said check valve and to said inlet and extending within said casing to a point above the normal level of such body of water; means disposed within said casing about said conduit for normally directing the flow of gas downwardly through such body of water; means disposed between said casing and said downwardly directing means for removing moisture fro-m said gas subsequent to its passage through such body of water; and means disposed within said holder for removing dust and moisture from said gas prior to its passage through such body of water.

10. A hydraulic back-pressure arrester comprising a casing having an inlet adjacent the lower end thereof and an outlet adjacent the upper end thereof, said casing being adapted to hold a body of water in the lower portion thereof and also adapted normally to permit the flow of a moisture-laden gas from the inlet to the outlet thereof; an inlet line including a check-valve, a conduit attached to said check-valve, a holder of substantially greater diameter than said conduit for collecting and delivering a gas to said conduit, said holder having one end attached to said conduit and the other end open, an inlet conduit connected to said check-valve and to said inlet and extending within said casing to a point above the normal level of such body of water; an inverted bell disposed within said casing and having the closed upper end thereof disposed above said inlet conduit, said bell also being disposed about said conduit and extending downwardly to a point adjacent the lower end of said casing and below the normal level of such body of water; means disposed between said bell and said casing for removing moisture from said gas subsequent to its normal passage through such body of water; and means disposed within said holder adjacent the open end thereof for removing dust and moisture from such gas prior to its passage through such body of water.

11. A hydraulic back-pressure arrester comprising a vertical gas inlet conduit, a capped tube disposed about said conduit, and an upright casing for housing said tube and adapted to provide a vessel for sealing liquid in which the lower end of said tube is immersed, said conduit and tube being spaced and arranged in fixed relation to provide an emergency reservoir therebetween for all of the sealing liquid in the event of a reversal of the gas flow.

MAURICE P. DE MOTTE.

CERTIFICATE OF CORRECTIOND Patent No. 2,161,700. June 6, 1959.

MAURICE P. DE MOTTE.

It is hereby certified that error appears in the printed specification of the'above numbered patent requiring correction as follows: Page i first column, lines 21, 22, and 25, claim 5, strike out the words and semicolon "and a plurality of baffles disposed between said casing and said bell above the normal level of said body of liquid;"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1959.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

